The necessity of fine-needle aspiration biopsy in surgical decision-making for thyroid nodules larger than 3 cm

Ultrasound-guided fine-needle aspiration biopsy (FNAB) is an essential diagnostic tool for detecting malignancy in thyroid nodules. The objective of this study was to evaluate the necessity of FNAB in the treatment decision-making process for thyroid nodules exceeding 3 cm in size. The records of patients who underwent thyroidectomy in our center between 2018 and 2023 were retrospectively reviewed. The study included patients with an index nodule size exceeding 3 cm. Exclusion criteria were missing data, treatment for a different oncological condition, recurrent disease, and purely cystic nodule. Patients were categorized into 2 groups based on the size of the index nodule: Group 1 included nodules measuring between 3 to 4 cm, and Group 2 included nodules 4 cm and larger. Demographic data, FNAB results, and histopathological findings were recorded. The specificity, sensitivity, false negative, and false positive rates of FNAB were calculated. There were 1935 patients who underwent thyroidectomy within the specified date range. In 359 of these patients, the index nodule size was 3 cm or more. There were 188 patients with nodule size between 3 and 4 cm. The mean age was 50.42 ± 13.34 years, and 257 patients were female (F/M ratio = 2.5/1). Fine needle aspiration biopsy was performed on 237 patients, resulting in 65 false negatives. Both the incidence of malignancy and the rate of FNAB false negatives were higher in nodules measuring 4 cm or larger. This study identified a high malignancy rate and a significant rate of false negatives in FNAB of thyroid nodules larger than 3 cm. These findings highlight the importance of carefully considering these factors in the surgical planning of such nodules.